Transportable commercial containers used in shipping, flying and trucking goods in commerce require a secure locking system to prevent tampering or theft of their contents. Locking systems currently used, while appearing to render these containers secure, nonetheless remain in jeopardy because at least one crucial member of the locking system is exposed and thus vulnerable to disengagement or distruction by determined criminals. The present invention provides a locking system which may be added to existing containers or containers in the process of being manufactured, rendering the access doors of these containers, whether a pair of swinging doors or at least one roll-up door, virtually tamper-proof. All of the parts to this locking system are concealed or otherwise shielded from forceable disengagement or distruction.